1. 6.3 Mendel and Heredity

2. Mendel laid the groundwork for genetics.
Gregor Mendel
Austrian monk
1800s
Mathematician
Most famous for correctly predicting the results
of meiosis before the discovery of chromosomes.
He recognized that traits are inherited as discrete units
(genes) from parental generation.
He was the first to describe how traits are passed.

3. Mendel laid the groundwork for genetics.
The study of biological inheritance patterns and variations in organisms.
Traits –
distinguishing characteristics that are inherited
ex. eye color, leaf shape, tail length
hereditary – passed from one generation to the next

4. Mendel’s data revealed patterns of inheritance.
Read about Mendel’s experiment p 177 – 179
Experimental Design
Purebred – type of organism whose ancestors are genetically uniform
Results
Cross – the mating of two organisms
Conclusions
Law of segregation – Mendel’s First Law
Organisms inherit two copies of each gene, one from each parent.
Organisms donate only one copy of each gene in their gametes. Thus, the two copies of each gene segregate during gamete formation.

5. 6.4 Traits, Genes, and Alleles

6. The same gene can have many versions.
gene – a piece of DNA that provides a set of instructions to a cell to make a certain protein
Each gene has a locus (specific location on a pair of homologous chromosomes).
Allele – any of the alternative forms of a gene that may occur
Each gene has two alleles, one from each parent.
Homozygous – two of the same alleles at a specific locus
Heterozygous – two different alleles at a specific locus

7. Genes influence the development of traits.
Genome – all of an organism’s genetic material
Genotype – the genetic makeup of a specific set of genes
Phenotype – the physical characteristics, or traits
Dominate allele – the allele that is expressed when two different alleles or two dominate alleles are present
Recessive allele - the allele that is only expressed when two copies are present